System and method for evaluating a formation using a statistical distribution of formation data

Patent metadata

Field	Value
Publication number	US-11099293-B2
Application number	US-201715773542-A
Country	US
Kind code	B2
Filing date	May 8, 2017
Priority date	May 8, 2017
Publication date	Aug 24, 2021
Grant date	Aug 24, 2021

Abstract

A system and method of evaluating a subterranean earth formation using a statistical distribution of formation data. The system comprises a logging tool and a processor in communication with the logging tool. The logging tool comprises a sensor operable to measure formation data and is locatable in a wellbore intersecting the subterranean earth formation. The processor is operable to calculate inversion solutions to the formation data, wherein each inversion solution comprises values for a parameter of the formation, and generate a statistical distribution of the parameter along one or more depths in the subterranean earth formation using the inversion solutions. The processor is also operable to identify peaks within the statistical distribution and select the inversion solutions corresponding to the identified peaks, generate a formation model using the selected inversion solutions; and evaluate the formation using the formation model to identify formation layers for producing a formation fluid.

First claim

What is claimed is:

1. A system for evaluating a subterranean earth formation, comprising:
a logging tool comprising a sensor operable to measure formation data and locatable in a wellbore intersecting the subterranean earth formation; and
a processor in communication with the logging tool and operable to:
calculate distance to bed boundary (DTBB) inversion solutions to the formation data using a DTBB inversion method, wherein each DTBB inversion solution comprises values for a parameter of the formation,
generate a statistical distribution of the parameter along one or more depths in the subterranean earth formation using the DTBB inversion solutions that satisfy a misfit threshold relative to the formation data for generating the statistical distribution,
identify peaks within the statistical distribution and select the DTBB inversion solutions corresponding to the identified peaks,
generate a formation model using the selected DTBB inversion solutions, and
evaluate the formation using the formation model to identify formation layers for producing a formation fluid.

2. The system of claim 1 , wherein the logging tool comprises a resistivity logging tool operable to measure the resistivity of the formation.

3. The system of claim 1 , wherein the processor is further operable to generate the formation model by calculating a mean of parameter values included in the selected DTBB inversion solutions for a measurement depth of the logging tool.

4. The system of claim 1 , wherein the parameter includes any one or any combination of horizontal resistivity, vertical resistivity, conductivity, anisotropy ratio, boundary position of formation layers, and a formation dip.

5. The system of claim 1 , wherein the statistical distribution comprises a histogram of the parameter, wherein the processor is further operable to generate the histogram by determining formation boundary positions among the DTBB inversion solutions and determining the frequency of formation boundary positions at each true vertical depth.

6. The system of claim 1 , wherein the processor is further operable to determine the uncertainty of a parameter based on the statistical distribution by identifying the width of a peak in the statistical distribution.

7. The system of claim 1 , wherein the DTBB inversion solutions comprise any one or any combination of a one-dimensional, a two-dimensional, or a three-dimensional inversion solution.

8. The system of claim 1 , wherein the processor is further operable to calculate the DTBB inversion solutions for formation data measured at a particular wellbore depth.

9. The system of claim 1 , wherein the processor is further operable to identify peaks within the statistical distribution based on a parameter frequency exceeding a threshold relative to an adjacent parameter frequency.

10. A method of evaluating a subterranean earth formation, comprising:
calculating distance to bed boundary (DTBB) inversion solutions to formation data measured with a sensor of a logging tool located in a wellbore intersecting the formation using a DTBB inversion method, wherein the DTBB inversion solutions comprise values for a parameter of the formation;
generating a statistical distribution of the parameter along one or more depths in the subterranean earth formation using the DTBB inversion solutions that satisfy a misfit threshold relative to the formation data for generating the statistical distribution;
identifying peaks within the statistical distribution and selecting the DTBB inversion solutions corresponding to the identified peaks;
generating a formation model using the selected DTBB inversion solutions; and
evaluating the formation model to identify a formation layer to produce formation fluids.

11. The method of claim 10 , wherein the logging tool comprises a resistivity logging tool operable to measure the resistivity of the formation.

12. The method of claim 10 , wherein the formation model is generated by calculating a mean of parameter values included in the selected DTBB solutions for a measurement depth of the logging tool.

13. The method of claim 10 , wherein the parameter includes any one or any combination of horizontal resistivity, vertical resistivity, conductivity, anisotropy ratio, boundary position of formation layers, and formation dip.

14. The method of claim 10 , wherein the statistical distribution comprises a histogram of the parameter, and wherein generating the histogram comprises determining formation boundary positions among the DTBB inversion solutions and determining the frequency of formation boundary positions at each true vertical depth.

15. The method of claim 10 , further comprising determining the uncertainty of a parameter based on the statistical distribution of formation boundary positions.

16. The method of claim 10 , wherein identifying the peaks comprises identifying the peaks based on a parameter frequency in the statistical distribution exceeding a threshold value relative to an adjacent parameter frequency.

17. A method of steering a drill bit in a subterranean earth formation, comprising:
calculating distance to bed boundary (DTBB) inversion solutions to formation data measured with a logging tool comprising sensors and located in a wellbore intersecting the formation using a DTBB inversion method, wherein the DTBB inversion solutions comprise values for a parameter of the formation;
generating a statistical distribution of a parameter of the formation along one or more depths in the subterranean earth formation using the DTBB inversion solutions that satisfy a misfit threshold relative to the formation data for generating the statistical distribution;
identifying peaks within the statistical distribution and selecting the DTBB inversion solutions corresponding to the identified peaks;
calculating a mean of the parameter values included in the selected DTBB solutions for a measurement depth of the logging tool to generate a formation mode; and
steering the drill bit through a formation layer identified using the formation model.

18. The method of claim 17 , wherein the logging tool comprises a resistivity logging tool operable to measure the resistivity of the formation; and the parameter includes any one or any combination of horizontal resistivity, vertical resistivity, conductivity, anisotropy ratio, boundary position of formation layers, and a formation dip.

Assignees

• Halliburton Energy Services Inc

Inventors

• Dong Weixin
• Wu Hsu-Hsiang

Classifications

• E21B41/00

  Equipment or details not covered by groups E21B15/00 - E21B40/00 · CPC title

• E21B7/04

  Directional drilling · CPC title

• G01V3/26 Primary

  operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device (with electromagnetic waves G01V3/30) · CPC title

• E21B49/00

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title

• E21B47/00 Primary

  Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) · CPC title